if i dont get an answer, i'm going to stave?

how do i lose weight? i'm 16 and i feel so fat. height:149 cm weight: 36 kg i just found out today when my doctor was measuring my bmi, i didnt expect the numbers to be that big. I want to drop to atleast 28 or 29 kilos, cos people say im short for a 16 year old girl so I guess 36 kilos is overweight .... any suggestions, please help, im desperate and if i only have 100 calories a day, will i acheve my goal? ps: please dont call me fat and be mean, i already know it.... honest answers only, thanks ..